In 1966, the American Numismatic Society, New York acquired a great rarity of a coin, minted in 553/1158. It was illustrated in the American Numismatic Society's Annual Report for 1966 (pl.III,2). George C. Miles gave its detail in "Coins of the Assassins of Alamut"(Orientalia Lovaniensa Periodica, 3-5, 1972-74, pp. 155-162). Its size is 14 mm., weighing 0.635 gm. Its obverse side bears the name, "Muhammad bin (Kiya) Buzrug Ummid" and in the marginal legend, the name of the mint, kursi al-Daylam and the date 553 A.H. (1158 A.D.) have been clearly inscribed. The reverse area begins with the Shiite formula: "Ali is the friend of God" and the next three lines read: "al-Mustapha li dinillah, Nizar" (Nizar, the chosen for the religion of God). These three lines are followed by the marginal legend: "amir al-mo'minin, salwat Allah alayhi wa-ala aba'ihi al-tahirin wa-abna'hi al-akramin" (the blessings of God be upon him and upon his ancestors, the pure ones; and upon his descendants, the most honourable ones).
George C. Miles reproduced the photographs of the following six coins:
There are few other coins minted at kursi al-Daylam with the same legends, differing only in dates.
It implies that the six coins from above had been struck during the Imamate of al-Mohtadi (530-552/1136-1157), and the two coins during the period of his successor, al-Kahir (552-557/1157-1162). It must be remembered that the early Imams in Alamut lived in concealment. They could show their slight appearances, but not whereabouts. None among them had taken power of the Nizari state at that time, and therefore, the name of the ruler, Muhammad bin Kiya Buzrug (532-557/1138-1162) was struck in the coins for governing the state. Paula Sanders however remarks in his "Ritual, Politics, and the City in Fatimid Cairo" (New York, 1994, p. 85) that, "The authority of the Fatimid caliph was challenged by the coins struck by the Nizaris at Alamut in the name of Nizar."
The above coins however bear the benedictory words, invoking the prayers for al-Nizar, his ancestors and his descendants. This antique and numismatic evidence further concludes that the descendants of al-Nizar in fact existed in Alamut, and rules out an idea of the historians, purporting the discontinuation of the Nizarid line. Ibn Khallikan (1211-1282) writes in his "Wafayat al-A'yan" (tr. de Slane, Paris, 1868, 1st vol., p. 160) that, "Nizar is the person from whom the Ismaili princes (Imams), the possessors of the fortress of Alamut and other castles in Persia; trace their descent."
Meanwhile, the Seljuq sultan Daud, who had severely domineered on the Ismailis in Azerbaijan and was becoming a major threat. In 538/1143, four Ismaili fidais had to kill him at Tabriz to avoid further massacres.